Higher Ext-groups in the triple product case

In this short note, we compute higher extension groups for all irreducible representations and deduce the multiplicity formula for finite length representations in triple product case.Comment: To appear in Math. Res. Let

Image Compression using Phase Diversity of Synthesis Filters

Abstract This paper presents enhancement of image reconstruction by comprehensively exploiting the phase diversity of adaptive synthesis filter bank. A novel approach of selection of synthesis delay filters in various reconstruction groups and possible placing configurations of optimal groups in adaptive sy nthesis filter bank have been explored. In contrast with linear phase synthesis filters, synthesis section is built with a set of filters, where each filter has different phase characteristics. Such adaptive formation of synthesis filter bank when employed in image compression shows optimal improvements in M SE/ PSNR over conventional filter bank

Brain MR Image Segmentation Based on an Adaptive Combination of Global and Local Fuzzy Energy

This paper presents a novel fuzzy algorithm for segmentation of brain MR images and simultaneous estimation of intensity inhomogeneity. The proposed algorithm defines an objective function including a local fuzzy energy and a global fuzzy energy. Based on the assumption that the local image intensities belonging to each different tissue satisfy Gaussian distributions with different means, we derive the local fuzzy energy by utilizing maximum a posterior probability (MAP) and Bayes rule. The global fuzzy energy is defined by measuring the distance between the original image and the corresponding inhomogeneity-free image. We combine the global fuzzy energy with the local fuzzy energy using an adaptive weight function whose value varies with the local contrast of the image. This combination enables the proposed algorithm to address intensity inhomogeneity and to improve the accuracy of segmentation and its robustness to initialization. Besides, the proposed algorithm incorporates neighborhood spatial information into the membership function to reduce the impact of noise. Experimental results for synthetic and real images validate the desirable performances of the proposed algorithm

Design of Fixed Wideband Beamformer through Improved Maximum Energy Approach

A maximum energy approach is investigated in this paper to design fixed wideband beamformer. This approach has been improved by integrating response variation (RV) into the target function to maintain the frequency invariant property of wideband beamformer over the whole passband. Two methods for designing null to suppress interference signal also have been proposed to make the wideband beamformer robust in complicated environment. Comparisons among other methods are provided to illustrate the effectiveness and enhancement of performance of the new approaches

Treatment of insomnia in myasthenia gravis—A prospective study on non-benzodiazepine hypnotics in the treatment of myasthenia gravis patients with insomnia

ObjectivesThis study aimed to evaluate the efficacy and safety of non-benzodiazepine hypnotics in the treatment of myasthenia gravis (MG) patients with insomnia.MethodsThis is a prospective longitudinal study. Outpatients who met the criteria for stable MG and insomnia diagnosis according to the International Classification of Sleep Disorders (third edition) were included in the study. They took a regular dose of non-benzodiazepine hypnotics (zolpidem 10 mg per night or zopiclone 7.5 mg per night) based on their own preferences. Patients received psychotherapy (including sleep health education) and were followed up for 4–5 weeks. Cases with lung diseases, respiratory disorders, or inappropriate use of hypnotic medications were excluded. The primary outcome is the difference in total Pittsburgh Sleep Quality Index (PSQI) score between baseline and the end of follow-up period. Secondary outcomes include the difference in Myasthenia Gravis Activities of Daily Living (MG-ADL) score, 7-item Generalized Anxiety Disorder Questionnaire (GAD-7), and the Patient Health Questionnaire-9 (PHQ-9) between baseline and the end of follow-up period and the safety of medication.ResultsA total of 75 MG patients with insomnia were included in this study. After 4–5 weeks of treatment, the total PSQI score and MG-ADL score were lower than baseline (p < 0.01). No patients had an increased MG-ADL score. The incidence rate of adverse events was 16.0% (12 cases), including dizziness (6 cases, 8.0%), drowsiness (3 cases, 4.0%), fatigue (2 cases, 2.7%), and nausea (1 case, 1.3%), all of which were mild. No patients had new onset breathing disorders.ConclusionNon-benzodiazepine hypnotics are safe and effective for stable MG patients who need insomnia treatment

Comparison of pulse position modulation and pulse width modulation for application in optical communications

Different modulation methods for optical wireless have different power and bandwidth efficiencies. Each approach has a direct bearing on the quality and effectiveness of wireless optical communications. As two prime examples, pulse position modulation (PPM) and pulse width modulation (PWM) are compared. The comparison includes the power and bandwidth efficiencies, the power spectrum distribution, and the ability to resist intersymbol interference. Compact system models of multilevel digital PPM (L-PPM), and multilevel digital PWM (L-PWM) are also introduced. The results show that L-PPM has advantages in power efficiency and an approximately uniform spectral distribution, whereas L-PWM has a greater ability to resist intersymbol interference. (c) 2007 Society of Photo-Optical Instrumentation Engineers